Biomedical Engineering Reference
In-Depth Information
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FIGURE 12.1
AFM of human enamel treated by acid etching only showing narrow grooves (black arrows) and flattened
perikymata ridges (white arrow) with cracks and many destructed areas of nontreated enamel surface (A); enamel
treated with acid etching and fluoride varnish showing moderately wide perikymata groove (black arrow) and
localized areas of destruction (white arrow) (B); enamel treated with acid etching and unfilled sealant group
showing wide perikymata grooves and flattened perikymata ridges (C); and enamel treated with acid etching
followed by proseal showing perikymata ridge and groove with obvious focal holes (frames are 50
50
m)
From Ref. [6] .
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FIGURE 12.2
Because all surfaces have irregularities that are large on a molecular level, real contact occurs only at peaks
of irregularities, called asperities. When interlocking occurs between the peaks and bottoms of the asperities,
resistance to movement occurs [7] .
12.3 Nanotechnology and gene therapy in orthodontics
Mandibular underdevelopment has been attributed to a variable interaction of genetic and environ-
mental factors, which is believed to be difficult to manipulate or stimulate. Bite jumping appli-
ances, also known as functional appliances (FAs), have long been claimed and used to enhance
mandibular growth in cases with deficient mandibles (mandibular retrognathism). A recent study
systematically reviewed reports on the effectiveness of FAs and concluded that the analysis of the
effect of treatment with FAs versus an untreated control group showed skeletal changes that were
statistically significant in the short term but unlikely to be clinically significant [9] .
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